kernel/iwn: Add a missing wlan_serialize_exit().
unlock_return.cocci: Add vn_unlock() and wlan_serialize_exit() tests.
kernel/bwn: Improve error handling in bwn_attach().

* Making sure to call wlan_serialize_exit() when bus_setup_intr() fails.

* Return the proper error values when bwn_attach() fails.
kernel/hammer2: Add two missing lockmgr(..., LK_RELEASE).
unlock_return.cocci: Add a nlookup_init()/done() test (which we pass).